When I first made my magician, I was certain I'd be I/L. I've recently learned that it is the inferior advancement, in terms of damage to F/P and in terms of leveling to Cleric/bishop. I still kind of want to be I/L, but I don't want to end up getting really frustrated/bored cause of low damage.. :/ So my question is, is F/P really all that more powerful? As in, is the damage a huge difference?
Don't worry, once they get to 4th job they both have nearly identical damage. Also F/P doesn't have mob skill until 3rd job, so I/L's get to 70 much faster.
All of those jobs have their advantages, of course. F/P is strong, yes, but have no good mob control until 3rd job, as Mekansm said. I/L has a little less damage late-game compared to F/P, but have great mobbing capabilities and are a breeze to train. Clerics have the obvious advantage of Holy Symbol, but they will A) Have to be dependant on parties, B) are not really fun to train, and C) THERE ARE TOO MANY. If you want to make a main, I'd personally choose I/L, especially if you're unfunded as this is (probably) your first character. Clerics are often made as HS mules, or to train main accounts. Hope this info helps.
They're only necessarily dependent on parties for high level bosses - as long as you've got reasonable equips (doesn't have to be anything fantastic) they can be pretty effective and cheap-to-run solo grinders. I'd definitely agree that there are too many, though!